Network call management in case of low battery condition of mobile communications terminals

ABSTRACT

In a mobile communications system which includes a mobile communications network and a battery-powered mobile communications terminal, a method including: receiving, at a mobile communications network apparatus subsystem, a notification of a low battery charge condition from the battery-powered mobile communications terminal, and having the mobile communications network apparatus subsystem inform at least one second user, different from a first user using the battery-powered mobile communications terminal, based on the received notification.

CROSS REFERENCE TO RELATED APPLICATION

This application is a national phase application based onPCT/EP2004/053706, filed Dec. 24, 2004.

FIELD OF THE INVENTION

The present invention generally relates to the field oftelecommunications, particularly to mobile communications networks, suchas for example GSM, GPRS/EDGE, UMTS mobile communications networks,allowing mobile users to communicate.

BACKGROUND OF THE INVENTION

In the past one or two decades, mobile communications terminals (e.g.mobile phones, user equipments, mobile stations, personal digitalassistants, pocket computers and the like) used for exploiting thecommunications capabilities offered by mobile communications networkshave experienced great improvements in performance.

An aspect that, in particular, has been improved concerns the operatingautonomy of the mobile communications terminal.

Mobile communications terminals are in fact powered by batteries: theimprovements in battery technology, in conjunction with the reduction ofpower consumption by the electronic circuitry of the mobilecommunications terminals, have significantly extended their operatingrange.

Nonetheless, the time operability of mobile communications terminals isstill relatively limited, and this continue to represent a problem to befaced.

Typically, the responsibility of checking the battery charge level, and,depending on it, taking a proper conduct so to avoid ending with anunusable mobile terminal due to full battery discharge, is totally up tothe user.

Completely relying on the fact that the user pay the due attention tothis aspect is not particularly effective, nor particularly safe. Infact, nothing ensures that the user realizes in due time the low levelof the battery charge and, in view of, e.g., his/her needs in theimmediate future, adopt the correct conduct, by for example rechargingthe battery, or limiting the mobile communications terminal usage.

Additionally, it may happen that when the user realizes of the lowbattery charge condition, the battery level is already so low that thecharge left is at best sufficient for placing/sending only one singlevoice call/message; this is in particular true when the battery hasalready been submitted to several charge/discharge cycles, consideringthat batteries degrade with time, so that an old battery may exhibit afaster charge fall than a new one.

In U.S. Pat. No. 6,236,326 a wireless telephone is described that whenthe battery nears depletion, and if a telephone call is not in progress,contacts the wireless telephone network and enables a call forwarding toa different number; if instead a telephone call is in progress, thewireless telephone plays an audible message to the party with whom thewireless subscriber is speaking, thereby informing the party that thewireless connection will soon be lost.

U.S. Pat. No. 6,704,583 describes a mobile telephone including a memorystoring telephone numbers, and a controller detecting a telephone numberof an incoming call, comparing the detected telephone number to thenumbers stored in the memory, and determining whether the incoming callis to be received, even when a voltage supplied by the voltage source isequal to or lower than a predetermined threshold.

Solutions in which a mobile communications terminal provides to themobile communications network indications about the battery charge havebeen proposed in the art.

For example, in WO 98/26622 the problems of call drops is faced. Amobile communications apparatus monitors the power level of its internalbattery power supply, and the measured power levels are reported to andstored by the base station or switching node of a serving network. If anongoing call should then be dropped, the stored power levels reported bythe mobile communications apparatus engaged in the dropped call areretrieved and processed to determine whether the battery failure is alikely cause of the call drop: in the affirmative case, an appropriatecause notation is made in association with a recording of the instanceof the call drop.

U.S. Pat. No. 6,408,172 is concerned about emergency calls placed withina cellular network. A battery status indicator associated with a callingmobile station during an emergency call is transmitted to the emergencycenter; the emergency center can provide special handling for suchcalls, such as displaying the low battery indicator to the emergencyoperator; in addition, the cellular network serving the mobile stationcan handover the call to a cell with lower power demands in order toprolong the battery life of the mobile station.

WO 98/10610 proposes a method for systematically scaling back theoperations of a mobile station as its battery is continuously dischargedby usage. Different mobile station operations are progressively disabledas the capacity of the battery falls below certain predeterminedthreshold levels: below the highest threshold level the mobile stationsends a registration cancellation message to the serving system so as toprevent the receipt of any page message, then disables the transmitoperation and enables only the receive operation. Below the lowestthreshold level the mobile station does not completely shut off alloperations, but instead allows the continuation of a minimum subset ofoperations, including the charging operation.

In EP 915 632 a base station of a wireless communications systemreceives battery power level information and other setup informationfrom mobile stations operating within the service area of the basestation during call setup procedures. Based on the battery power levelinformation and other setup information, the base station assignsfrequency channels to the mobile stations so that those mobile stationshaving battery power levels below a threshold value are assignedfrequency channels that have lower interference levels than frequencychannels assigned to other mobile stations. The frequency channelassignments are transmitted to the mobile stations.

In U.S. Pat. No. 6,072,784, scheduling priorities in a CDMA (CodeDivision Multiple Access) wireless communications system are adapted toconserve battery power in mobile terminals operating within the system.The transmit power of all mobile stations is controlled by the basestation (which receives the battery power level information during callsetup procedures) to optimally conserve the battery power of aparticular mobile station reporting a low battery condition. The basestation adapts scheduling priorities for the mobile terminals toexpedite wireless transmission from those mobile terminals reporting lowbattery power levels.

SUMMARY OF THE INVENTION

The Applicant has observed that the solutions known in the art are notparticularly satisfactory.

For example, in connection with the solution proposed in U.S. Pat. No.6,704,583, the Applicant observes that, in case the incoming call isallowed to be received, the calling user is completely unaware of thelow battery condition of the called user, and may thus not be preparedto the fact that the remaining battery charge is sufficient only for avery short conversation, thereby the call may irremediably fall beforethe important information is transferred. Moreover, the processing powerrequested to the mobile phone to detect and compare the telephonenumbers of the incoming calls with those stored in memory causes afurther decrease of the battery charge.

The solution set forth in WO 98/26622 has the purpose of allowing anetwork operator evaluate whether the call drops are caused by animproper working of the network infrastructure apparatus, or instead bythe fact that the users involved in the dropped calls run out ofbattery, and so to limit the interventions on the network. The serviceis not at all directed to the users, which do not take any directadvantage of it.

In respect of WO 98/10610, the Applicant observes that the solutionproposed simply anticipates the deregistration of the user to a time atwhich the terminal still has some battery power.

The Applicant has observed that it would be useful to make third partiesaware of the fact that the user mobile communications terminal isexperiencing a low battery charge condition. In such a way, thirdparties could limit or avoid calls directed to the mobile communicationsterminal, so as to limit the decrease of the battery charge of thelatter. Furthermore, a third party, being aware of a low batterycondition of a mobile communications terminal to which a call may be oris being placed, could take a suitable decision (e.g. postpone the call,or keep the call short in time) in order to limit or avoid a risk ofloosing valuable information during a call due to an abrupt terminationof the latter. A valuable service is thus given both to a user who isexperiencing a low battery condition of its mobile communicationsterminal and to a third party considering a communication with suchuser.

The Applicant has accordingly devised a solution that allowsimplementing a service, at the network level (and particularly at theservice application level, without substantially impacting the core andaccess network infrastructure), that is adapted to take notice of thefact that mobile communications terminals experience a battery powershortage, and to consequently inform third parties.

According to a first aspect of the present invention, there is providedin a mobile communications system comprising a mobile communicationsnetwork (105, 130, 135, 155, 165, 170) and a battery-powered mobilecommunications terminal (110 a), a method comprising:

receiving, at a mobile communications network apparatus subsystem, anotification of a low battery charge condition from the battery-poweredmobile communications terminal, and

having the mobile communications network apparatus subsystem inform atleast one second user, different from a first user (115 a) using thebattery-powered mobile communications terminal, based on the receivednotification.

Briefly stated, in a mobile communications system comprising a mobilecommunications network and a battery-powered mobile communicationsterminal, a notification of a low battery charge condition from thebattery-powered mobile communications terminal is received at a mobilecommunications network apparatus subsystem.

The mobile communications network apparatus subsystem inform at leastone second user, different from a first user using the battery-poweredmobile communications terminal, based on the received notification.

According to a second aspect of the present invention, there is provideda mobile communications system (100) comprising a mobile communicationsnetwork (105, 130, 135, 155, 165, 170; 140, 145, 150, 155, 165, 170),characterized in that:

a mobile communications network apparatus subsystem is provided which isadapted to receive from a battery-powered mobile communications terminal(110 a; 110 b) a notification of a low battery charge condition, and toinform at least one second user, different from a first user (115 a)using the battery-powered mobile communications terminal, based on thereceived notification.

The mobile communications system comprises a mobile communicationsnetwork, and a mobile communications network apparatus subsystem isprovided which is adapted 10 to receive from a battery-powered mobilecommunications terminal a notification of a low battery chargecondition, and to inform at least one second user, different from afirst user using the battery-powered mobile communications terminal,based on the received notification.

BRIEF DESCRIPTION OF THE DRAWINGS

features and advantages of the present invention will be made apparentby the following detailed description of an embodiment thereof, providedmerely by way of non- limitative example, description that will beconducted making reference to the annexed drawings, wherein:

FIG. 1 pictorially shows a communications networks infrastructureadapted to provide a service implementing a method according to anembodiment of the present invention;

FIG. 2 schematically depicts the structure of a database of users'telephone numbers in respect of a subscriber user of the service;

FIG. 3 depicts, in terms of functional blocks, the structure of ageneric mobile communications terminal according to an embodiment of thepresent invention; and

FIG. 4 is a schematic flowchart illustrating in a simplified way some ofthe steps of the method according to an embodiment of the presentinvention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S) OF THE INVENTION

Referring to the drawings, FIG. 1 shows schematically an infrastructureof mobile communications networks , particularly focusing on the serviceand control layers, according to exemplary, non limitative, embodimentsof the present invention. The infrastructure of mobile communicationsnetworks is globally identified by reference numeral 100.

The infrastructure 100 comprises a Circuit-Switched (CS) mobilecommunications network 105, for example a GSM network (i.e., a mobilecommunications network complying with the Global System for Mobilecommunications standard) or a Circuit Switched UMTS network (i.e.,Universal Mobile Telecommunications System).

In a way per-se known in the art, the CS network 105 includes (in theexemplary case of a GSM network) a plurality of Base Station Subsystems(BSSs), each one providing coverage for mobile communications in arespective geographic region. The generic BSS comprises a plurality ofBase Transceiver Stations (BTSs), each one covering a respective area,typically referred to as a “cell”, within the region covered by the BSS;the generic BTS communicates with, i.e., handles thetransmission/reception of signals to/from the mobile communicationsterminals, such as a mobile communications terminal 110 a of a user 115a shown in the drawing, which are located in the BTS's cell. Typically,several BTSs are connected to and controlled by a same Base StationController (BSC), a network unit that, roughly speaking, instructs thedifferent BTSs about the information to be transmitted to/received fromthe mobile communications terminals on specified physical, radiocommunication channels.

Groups of different BSSs are connected to respective Mobile SwitchingCenters (SCs); the generic MSC performs the function of gateway to otherMSCs of the same mobile communications network 105, to the MSCs of othermobile communications networks (of different network operators), to oneor more wired, Public Switched Telephone Networks (PSTNs), like a PSTN120 shown in the drawing. The MSC is associated with a Home LocationRegister (HLR), containing subscription data of users subscriber to themobile communications network, particularly mobile phone numbers, andwith a Visitor Location Register (VLR), containing information on wherethe various users are located at a given time, i.e., under which cell ofthe mobile communications network 105 the users' mobile communicationsterminals are registered at that time. Based on this information, theMSC switches, i.e., properly routes calls from callers to called users.

In an embodiment of the present invention, the CS network 105 is orincludes a UMTS network. Without going into details with the UMTSarchitecture (which is similar to the GSM architecture just outlined),the important aspect, in the considered context, related to the UMTSnetwork architecture is that it furnishes a richer set of services tothe user than the GSM architecture (e.g., a CS videocall service).

The network infrastructure 100 comprises a subsystem of networkapparatuses cooperating for providing services according to the presinvention.

To this purpose, according to an embodiment of the present invention astructure of Network Intelligence (NI) is provided in association withthe CS mobile network 105.

In particular, according to an embodiment of the present invention, theNI structure includes an Open Service Access (OSA) gateway 130, by meansof which the CS mobile network 105 interfaces with an OSA ApplicationServer (AS) 135, wherein the logic of one or more CS mobile networkservices is implemented.

The OSA gateway comprises two different entities: the OSA ServiceCapabilities Systems (SCSs) and the OSA framework. The OSA SCSs are theOSA gateway functionalities that enable the applications (running on theOSA AS) to access the underlying mobile network resources (e.g.resources for call control and user interaction). The OSA frameworkallows, among other functionalities, the SCSs authentication andregistration and enables the application access the network resources.

In another embodiment of the present invention, instead of exploiting anOSA gateway and an OSA AS, the mobile network control layer and themobile network application layer functionalities are implemented bymeans of an Intelligent Network (IN) structure, the basic element ofwhich is the Service Control Point (SCP), connected to the underlyingMSCs of the CS network 105 and running the service logic of the networkservice according to the invention embodiment herein described.

The mobile communications networks infrastructure 100 further comprisesa Packet-Switched (PS) mobile communications network 140, such as forexample a GPRS (General Packet Radio Service) or an EDGE (EnhancedData-rate for GSM Evolution) network or PS UMTS network, allowing mobileusers, provided with suitable mobile communications terminals, such as auser 115 b owning a mobile communications terminal 110 b, to benefit ofa PS-based data exchange capability, for example in order to access apacket-based network, typically the Internet, and exploit servicesoffered by specific Internet servers.

Without entering into excessive details, known in the art and notrelevant to the understanding of the invention embodiment hereindescribed, a PS mobile communications network 140 in accordance with theGPRS and the UMTS standards essentially is a CS mobile network add-up,being a technology compatible with the CS mobile networks, that supportspacket-based data communication, thereby enabling data transfer at aspeed higher than that allowed by pure CS mobile networks.

In short, the PS mobile network includes Gateway GPRS Support Nodes(GGSN) that act as an interface between the mobile communicationsnetwork and other, external packet data networks, such as the Internet,or other PS mobile communications networks (e.g., of other networkoperators). The GGSNs exchange data packets with Serving GPRS SupportNodes (SGSNs), each one associated with one or more respective BSSs ofthe associated GSM network, e.g., the GSM network 105, through PacketControl Units (PCUs), and routes the data packets received from theGGSNs to the proper destination mobile communications terminals, locatedin the geographic area covered by the respective BSS (or by one of therespective BSSs). In particular, the generic SGSN keeps track of thegeographical location of the UEs, so as to know where the data packetsare to be routed in order to be delivered to the intended destinationmobile communications terminals. The PCU converts the data packets,received from the respective SGSN, into data streams adapted to beingtransmitted “over the air”, by one of the BTSs, exploiting the radioresources of the CS mobile communications network; similarly, datastreams transmitted by the mobile communications terminals “over theair” and received by the BTSs are converted into data packets, fortransmission to the respective SGSN.

Also schematically shown in FIG. 1 is a 3GPP-compliant IP (InternetProtocol) Multimedia Subsystem (IMS) infrastructure 145 associated withthe PS mobile communications network 140 (3GPP stands for 3^(rd)Generation Partnership Project), for enhancing the packet-basedcommunications capabilities of the network by defining an open IP-based(more generally, packet-based) service infrastructure that enables aneasy deployment of new rich multimedia communications services mixingtelecom and data services, and particularly person-to-person IPmultimedia services.

Briefly, the basic elements of the IMS infrastructure 145 include CallSession Control Functions (CSCFs), including Proxy Call Session ControlFunctions (P-CSCFs) connected to respective Serving Call Session ControlFunctions (S-CSCFs); roughly speaking, the P-CSCFs are the interfacebetween the mobile communications terminals and the IMS infrastructure145, and behave as proxy, accepting requests from the mobilecommunications terminals and internally managing or forwarding them to,e.g., the S-CSCFs; the S-CSCFs can in turn behave as a proxy, acceptingthe incoming requests and managing them internally, or forwarding themto other elements of the IMS infrastructure, such as the InterrogatingCall State Control Functions, which is the interface to operator'snetwork. Within the IMS infrastructure, the signaling is compliant tothe SIP (Session Initiation Protocol), an IETF (Internet EngineeringTask Force) proposed standard for setting up sessions between one ormore clients in IP-based networks.

The (S-CSCFs) of the IMS infrastructure 145 colloquiate with a SIPapplication server 150, managing the SIP service logic for the IMSinfrastructure 145.

For the sake of simplicity, for the purposes of the present description,by “call” 10 there is intended indifferently a telephone call (includinga videocall) in the CS network, or an IP session in the PS network;similarly, by “message” there is intended indifferently a‘telephony-related message’ (e.g., a USSD, an SMS, an MMS message) or an‘Internet-related message’ (e.g., a Presence message and Instantmessage).

According to an embodiment of the present invention, a network serviceis implemented managing a low battery charge condition of the mobilecommunications terminals. In particular, in an embodiment of the presentinvention, the OSA application server 135 and the SIP application server150 interact with a battery status server 155, responsible of memorizinginformation (schematically depicted as a table 190) about a batterycharge level of the mobile communications terminals of mobile users,such as the users 115 a and 115 b, particularly information about acondition of low battery charge level. Typically, mobile users wishingto benefit of such a network service may be requested to subscribe forit at the network operator.

A mobile users' profile database 165 related to the service is furtherprovided, wherein individual profiles of mobile users subscribers to thenetwork service are stored.

The users' profile database may be provisioned either from the serviceprovider or the subscribers: in the latter case, the generic subscribercan provision the database via e.g. a web interface (i.e. via IP access,in case the subscriber is IP-enabled), or via SMS messages, or via USSD(Unstructured Supplementary Service Data) messages, or the like (asknown, USSD is a technology peculiar of the GSM making possibletransmission of information via alphanumeric messages—i.e. composed bythe characters *, #, numerical and literal—over the GSM signalingchannels).

In particular, as schematically depicted in FIG. 2, according to anembodiment of the present invention the profile 200 of the genericmobile user, like the user 115 a or the user 115 b, stored in thedatabase 165 may include a first list (“friends list”) 205 a of one ormore telephone numbers to which that user wishes that a notification ofthe state of low battery charge of his/her mobile communicationsterminals is sent, such as for example a fixed (PSTN) telephone numberand/or a mobile telephone number of another user 115 c, or his/here-mail address. More generally, the database 165 includes anyinformation suitable to address to the user 115c (through one or more ofhis communications terminals, globally indicated in FIG. 1 by 175 andincluding for example a mobile phone, and/or wired telephone, and/or acomputer connected to/connectable to an IP network 190, possibly via adial-up connection) a notification (of whichever type) of the lowbattery charge condition of the terminal 110 a, 110 b of the user 115 a,115 b. For example, an SMS (Short Messaging Service) or MMS (MultimediaMessaging Service) message, a voice message, an e-mail message, anInstant Message (IM), provided that the user 115 c has an IMS-compliantmobile communications terminal 175, may be sent to the “friend” user 115c.

The mobile users' profile database 165 may additionally include, foreach subscriber user, a second list (“white list”) 205 b of one or moretelephone numbers (provisioned on the users' profile database as the“friends list” with the same provisioning options previously described)from which the user wishes to receive possible calls (possibly SMSmessages, MMS messages, IMs) even if the state of battery charge ofhis/her mobile communications terminal is low (this second list mayinclude one or more of the telephone numbers of the friends list).

Coming back to FIG. 1, according to an embodiment of the presentinvention, a location server 170 is additionally provided, responsibleof storing location information adapted to identify a geographicallocation of the generic subscriber mobile user when the user's mobilecommunications terminals reaches and notifies to the network the lowbattery charge condition. The location information may for example bederived from the VLRs of the mobile communications network or from anysuitable localization system.

A block labeled 195 identifies a Short Messaging Service Center (SMS-C)assumed to be compliant to both the CS and the PS networks standards;the SMS-C 195 manages the distribution of SMS message, and communicateswith the CS mobile network 105, the PS mobile network 140, the OSAapplication server 135 and the SIP application server 150.

It is observed that albeit depicted as separate blocks in the drawing,one or both of the battery status server 155 and the location server 170may be functions implemented by either the physical apparatus runningthe OSA application server 135, or the SIP application server 150, orboth. Moreover, also the OSA application server 135 and the SIPapplication server 150 may be implemented on the same physicalapparatus.

It is also remarked that although in the description provided in theforegoing the existence of both a CS- and a PS-mobile communicationsnetworks has been considered, for the sake of completeness, this is notto be construed as a limitation of the present invention, which might infact be applied also in scenarios where only one mobile communicationsnetwork exist, either the CS-based or the PS-based.

The notification of the reached condition of low battery charge to themobile communications network is responsibility of the mobilecommunications terminals, which preferably automatically issue suchnotification. FIG. 3 depicts very schematically, in terms of functionalblocks relevant to the understanding of the invention embodiment hereindescribed, a structure of a generic mobile communications terminal, likefor example the mobile communications terminal 110 a. It is observedthat despite the mobile communications terminals adapted to operate witha PS-based mobile communications network like the PS mobile network 140,particularly mobile communications terminals complying with the IMSstandard, may differ from mobile communications terminals capable ofoperating in a CS-based mobile communications networks, like the GSMnetwork 105, the discussion herein below is sufficiently general to beapplicable to any kind of mobile communications terminal.

A data processor, e.g., a microprocessor 305 governs the operation ofthe mobile communications terminal. The mobile communications terminalcommunicates, over a bus 307, with peripheral units comprising inparticular a Read Only Memory (ROM) 310, storing the microcoderepresenting the program to be executed by the microprocessor 305, and aworking memory, typically, but not only, a Random Access Memory (RAM)315, exploited by the microprocessor 305 for the program execution andfor the temporary storage of data. A transmitter/receiver circuitry 320allows radio communication with the network's radio access front-end.The mobile communications terminal includes a (removable andinterchangeable) Subscriber Identity Module (SIM) 325, which is anIntegrated-Circuit (IC) smart-card module used primary forauthentication and registration purposes of the mobile communicationsterminal in the mobile communications network, and having its own dataprocessing and storage capabilities.

The hardware of the mobile communications terminal, particularly themicroprocessor 305, the ROM 310, the RAM 315, the TXRX section 320, theSIM 325 (as well as a display, a keyboard, a microphone, a loudspeaker,not shown in FIG. 3 for simplicity), is powered by a battery 350.

Also schematically depicted in FIG. 3 is a (partial) content of theworking memory 315 of the mobile communications terminal in operation.An operating system 330 handles the interface to peripheral hardware,schedules tasks, allocates storage, or the like; the operating system330 may for example be the known Symbian OS by Symbian Ltd.

When the mobile communications terminal is put in operation, a batterycharge level monitoring client module 335 is running, which isresponsible of monitoring the battery charge level. For example, themicroprocessor 305 may be provided with an analog input 350 a to whichthere is associated an embedded Analog-to-Digital (A/D) converter,adapted to measure the battery voltage for determining the batterycharge level.

The measured battery charge level is then provided to the battery chargelevel monitoring client module 335, for processing. It is observed thatalmost all of the current mobile communications terminals implement abattery charge level monitoring function, usually adapted to display tothe user an indication of the remaining battery charge, and to beep whena too low battery charge level is reached: the battery charge levelmonitoring client module 335 according to an embodiment of the presentinvention may be implemented as an expansion of these functions alreadyimplemented. In particular, the battery charge level monitoring clientmodule 335 is adapted to compare the measured battery charge level withone or more predetermined thresholds, for example, in an embodiment ofthe present invention, an upper threshold TH1 and a lower threshold TH2(stored for example in the ROM 310, and whose value may depend on theparticular type of mobile communications terminal, for example on thetype of battery 350).

Preferably, hysteresis is implemented: the thresholds TH1 and TH2 areboth associated with two different values, respectively said TH1 d (TH1discharge) and TH1 c (TH1 charge), and TH2 d (TH2 discharge) and TH2 c(TH2 charge); the notations “discharge” and “charge” indicate thecrossing of the two thresholds TH1 and TH2 during a battery dischargephase, and a successive battery recharge phase, respectively.

For both the thresholds TH1 and TH2 the discharge level TH1 d, TR2 d islower than the charge level TH1 c, TH2 c. In other words, while thebattery is discharging (during normal use of the terminal), thereference thresholds exploited by the module 335 as comparison valuesare the discharge thresholds TH1 d, TH2 d; on the contrary, during are-charge of the battery, or when the battery is replaced, thethresholds used by the module 335 as comparison values are the chargethresholds TH2 c, TH1 c.

In a preferred embodiment of the invention, the battery charge levelmonitoring client module 335 is further adapted to cause the mobilecommunications terminal notify to the mobile communications networkinformation concerning its battery charge level, particularly of thecrossing of the thresholds TH1 d, TH2 d, TH2 c and TH1 c; for example,the functions of a USSD client module 340 are exploited in order to sendUSSD messages to the network HLR; a USSD gateway, identified by 180 inFIG. 1, is exploited for properly routing the USSD message between theHLR and the application server, as described later on. Alternatively,the information concerning the mobile communications terminal's batterycharge level may be communicated to the mobile communications networkvia SMS messages, or Instant messages, or Presence messages (in the caseof an IMS mobile terminal). In case the mobile communications terminalis IMS-compliant, like the terminal 110 b, the battery charge levelmonitoring client 335 may exploit a SIP signaling module (identified inFIG. 3 by the same reference numeral 340, for the sake of simplicity)for providing to the IMS network the information concerning the mobilecommunications terminal's battery charge level.

In another embodiment of the invention, the client 335 on the mobilecommunications terminal just signals to the subscriber user the crossingof the thresholds TH1 d, TH2 d, TH2 c and TH1 c, and let the subscriberthe option to notify to the mobile communications network the differentstates of the battery (via USSD messages, SMS messages, PresenceMessages or Instant Messages).

It is intended that at least some of the functions described in theforegoing, particularly the battery charge level monitoring clientmodule 335 and/or the USSD client module 340 might be executed by thedata processing units of the SIM 325, instead of by the microprocessor305.

In operation, a user subscribes to the network service; his/her mobilecommunications terminal monitors the battery charge level and notifiesto the network events relating to its battery charge level, particularlythe fall of the charge level below one or more threshold levels TH1 d,TH2 d). The network consequently informs third parties based on thereceived notification. For example, another user trying to place a callto the user experiencing a low battery charge may be informed of thiscritical condition by a courtesy message, and he/she may be given theoption of whether to continue with or release the call. In order toinform third parties, the network may additionally or alternatively sendSMS messages, MMS messages, Instant messages or any other notificationto a restricted, user-defined list of other users. In this way, aservice is given to both a user that is experiencing a low batterycondition of his/her mobile communications terminal, and a third partythat wants to place a call (or send a message) to such user. The thirdparty has the option of not placing or continuing with the call, or tokeep the call short in time, so as to limit a risk of loosing valuableinformation due to an abrupt termination of the call. On the other hand,the user can take advantage of a reduced number of received calls (ormessages), thus saving battery, so as to maintain, e.g. the possibilityto place emergency calls or the like.

In the following, an exemplary embodiment of the present invention willbe described in detail, making reference to the simplified flowchart ofFIG. 4 and to the infrastructure of FIG. 1, by which the mobilecommunications network, in addition to informing third parties based ona notification of low battery condition received from a subscriberuser's mobile communications terminal, also manages calls/messagesdirected to that user taking into account the low battery chargecondition.

In the flowchart, for the sake of simplicity, a block labeled byreference numeral 400 (“network”) is intended to include the CS mobilenetwork 105, the OSA gateway and application servers 130 and 135, thebattery status server 155, the database 165, the location server 170,the USSD gateway 180.

It is observed that the users wishing to benefit of the network serviceaccording to the embodiment of the invention herein described shouldpreliminary subscribe for it; upon subscribing, suitable resources inthe battery status server 160, in the profiles database 165 and in thelocation server 170 are defined and reserved to the new subscriber user,moreover, upon subscription, a trigger is set at the level of theHLR/VLR, and it is checked during the call switching and routing fromthe network, for example at the MSCs of the GSM network 105 in respectof the subscriber user, thereby the control of any call (and, possibly,of any message, such as SMS messages, MMS messages or Instant Messages),directed thereto is passed over to the OSA application server 135 or theSIP application server 150, which, based on the service logic, willmanage the calls (and the messages), for example in the way that willnow be described.

At the mobile communications terminal 110 a, the battery charge levelmonitoring client module 335 periodically checks the level of charge ofthe battery 350 (block 405); this can be done for example from time totime, as a routinely task during the mobile communications terminaloperation. The detected battery charge level is compared to the first,higher predetermined threshold TH1 (decision block 410), particularly tothe discharge threshold TH1 d associated with the upper threshold TH1;in case the battery charge level is found to be higher than thethreshold TH1 d (exit branch N of decision block 410), no particularaction is taken, and the operation of the mobile communications terminal110 proceeds as usual (connector J1). If instead the battery chargelevel is found to be equal to or lower than the threshold TH1 d (exitbranch Y of decision block 410), the battery charge level monitoringclient module 335 invokes the USSD client module 340 to cause the mobilecommunications terminal 110 a notify the network 400, via an USSDmessage, the reached low battery charge condition (upper threshold).(block 415). Alternatively, the mobile communications terminal 110 a maynotify the network 400 by means of an SMS message or in any othersuitable way, the invention being not restricted to a particular way ofnotifying the network of the reached low battery charge condition.

The USSD message sent by the mobile communications terminal 110 a isreceived at the HLR of the network 105, which forwards it to the USSDgateway 180; the USSD gateway 180 routes the USSD message to the OSAapplication server 135 (block 420). The OSA application server 135communicates with the battery status server 155 to cause the storage ofthe signaled low battery charge condition (as schematically depicted inFIG. 1, in the table 190 relating to the user 115 a a flag correspondingto the higher threshold TH1 is set) (block 425).

Optionally, the OSA application server 135 further causes the locationserver 170 to store a location indication adapted to identify thecurrent geographic location of the terminal 110 a (block 430). Thelocation indication may for example be derived from the VLRs of the GSMnetwork 105, or from any other localization service.

In consequence to the notification, third parties can be informed by thenetwork of the low battery charge condition experienced by the mobilecommunications terminal 110 a. In particular, users whose telephonenumbers are in the first (friends) list 205 a in the database 165 can benotified of the low battery condition of the terminal 110 a of the user115 a.

To this purpose, the OSA application server 135 retrieves from thedatabase 165 the telephone numbers listed in the first list 205 a, andissues a notification to the friends users, so as to inform them of thelow battery charge of the terminal 110 a of the user 115 a (block 435).The notification can be made in any suitable form, such as for exampleby way of an SMS message, or an USSD message, or an MMS message, or byexploiting an Interactive Voice Response (IVR) service 185, througheither the USSD gateway 180 or the OSA gateway 130, or by way of anInstant Messaging notification over the IMS network, or even by means ofan e-mail message, depending on the type of communications terminal ofthe destination user (the latter piece of information may be, forexample, stored in the database 165, in the list 205 a, associated withthe telephone number of the user).

The generic friend user whose telephone number is in the list 205 areceives the notification from the network, for example in the form ofan SMS message at his/her mobile communications terminal 175, and thenotification is displayed to him/her (block 440).

Optionally, the notification issued to the friend users whose telephonenumbers are in the list 205 a may include information, retrieved fromthe location server 170, adapted to identify where the user 115 a waswhen his/her mobile communications terminal reached the low batterycharge level condition, or other information personalized from thesubscriber (e.g. drawings or photos).

Totally similar actions are performed in case the mobile communicationsterminal is an IMS-compliant mobile communications terminal, like themobile communications terminal 110 b. In particular, instead of the USSDmessage, a SIP signaling can in that case be exploited, for notifyingthe SIP application server 150 of the reached low battery chargecondition; similarly to the OSA application server 135, the SIPapplication server 150 communicates with the battery status server 155to cause the storage of the signaled low battery charge conditioninformation and, optionally, with the location server 170, to causestorage of the geographic location information. The SIP applicationserver 150 then retrieves from the database 165 the telephone numbers inthe first list 205 a, determines the type of communications terminalsthat numbers correspond to, and issues a notification (in a form adaptedto the type of communications terminals) to these users so that they areinformed of the low battery charge of the user's mobile communicationsterminal 110 b. The generic user whose telephone number is in the list205 a receives the notification.

It is observed that the first threshold TH1, and particularly theassociated discharge threshold TH1 d should be set sufficiently high, sothat after the mobile communications terminal has reached thecorresponding battery charge level, there is sufficient charge left toallow the mobile communications terminal work for a reasonable period oftime.

The friend users that received the notification of the low batterycharge condition, being informed of such situation, may thus adopt thebest behavior in order to preserve the remaining battery charge in themobile communications terminal 110 a (or 110 b) of their friend 115 a(respectively 115 b). For example, they can decide to avoid placingunnecessary calls/sending unnecessary messages.

The detected battery charge level is then compared to the second, lowerpredetermined threshold TH2 (decision block 445), particularly to thedischarge threshold TH2 d. It is pointed out that albeit in theschematic flowchart of FIG. 4 this action is depicted as following theactions of blocks 410 and 415, this chronological order is not strictlynecessary; moreover, the comparison of the detected battery charge levelwith the second threshold TH2 d may be done at a later time, forexample, at a subsequent invocation of the battery charge levelmonitoring task.

If the detected battery charge level is found to be higher than thethreshold TH2 d (exit branch N of decision block 445), no further actionis taken. If instead the detected battery charge level is found to beequal to or lower than the second, lower threshold TH2 d (exit branch Yof decision block 445), the battery charge level monitoring clientmodule 335 invokes again the USSD client module 340 to cause the mobilecommunications terminal 110 a notify the network 400, via an USSDmessage, the new low battery charge condition (block 450). As in theprevious case, the USSD message sent by the mobile communicationsterminal 110 a is received at the HLR of the network 105, which forwardsit to the USSD gateway 180, and the USSD message is then routed to theOSA application server 135 (block 455). The OSA application server 135communicates with the battery status server 155 to cause the storage ofthe newly reached low battery charge (lower threshold TH2 d) conditionsignaled by the mobile communications terminal 110 a (block 460).Optionally, the OSA application server 135 further causes the locationserver 170 to store an indication adapted to identify the currentgeographic location of the mobile communications terminal 110 a.

In consequence to this further notification by the mobile communicationsterminal 110 a, the network can block incoming calls/messages directedto the mobile communications terminal 110 a, so as to save the remainingbattery life. In particular, the network may perform a selectivefiltering of the incoming calls/messages, depending on the useroriginating the incoming call/message; for example, calls placed ormessages sent by users whose telephone numbers are not in the secondlist 205 b in the database 165 are blocked. A courtesy message can beexploited for informing the calling users in these cases.

In an exemplary embodiment of the present invention, the management ofthe incoming calls/messages by the network is the following. The case ofan incoming call is considered first.

As mentioned in the foregoing, when the user 115 a subscribes to thenetwork service, a trigger is set at the HLR/VLR level of the CS network105. Thanks to the trigger being set, any incoming call directed to themobile communications terminal 110 a is passed over to the OSAapplication server 135. Referring to FIG. 4, let it be assumed that acall is placed to the mobile communications terminal 110 a of the user115 a, by either a “friend” user, i.e., a user whose telephone number,e.g. mobile, telephone number, is included in the second list 205 b(block 465 a) or a “non-friend” user, that is a user whose, e.g. mobile,telephone number is instead not included in the list (block 465 b). TheOSA application server 135 receives and takes control of the calls(block 470), and contacts the battery status server 160 to check whetherthe mobile communications terminal 110 a of the user 115 a has notifiedany low battery charge condition (block 475). In case no suchnotification has been made, or the mobile communications terminal 110 ahas notified only the reaching of the upper threshold TH1 (inparticular, the threshold TH1 d), the OSA application server 135forwards the incoming call to the user's mobile communications terminal110 a without performing any further control. For example, the OSAapplication server 135 may further check if the flag “TH2”,corresponding to the reaching of the lower discharge threshold TH2 d isset in the table 190 held by the battery status server 160) (decisionblock 480). In the negative case (exit branch N of decision block 480),i.e. if the flag “TH2” is not set, the incoming call is forwarded to andreceived at the mobile communications terminal 110 a (block 490),irrespective of who is the calling user. The user 115 a may as usualdecide whether or not to accept the incoming call and answer.

In case instead the OSA application server 135 finds that the flag “TH2”is set (exit branch Y of decision block 480), the OSA application server135 looks at the database 165 (block 491) and checks whether the(telephone number of the) calling user is in the second list 205 b(decision block 492). In the affirmative case (exit branch Y of decisionblock 492), before forwarding the telephone call to the destinationuser's mobile communications terminal 110 a the OSA application server135 may inform the calling user of the low battery charge conditioncurrently experienced by the called user's mobile communicationsterminal 110 a, so as to make the calling user aware of this situationand allow adopting the best conduct (block 493); this can be done forexample by routing first of all the calls to the IVR 185 (or to the MSCservice) in order to play an announcement to the caller, and only afterthe end of the announcement, route the call to the subscriber. Thecalling user, in addition to being informed of the low battery conditionof the caller user, may also be given the possibility to choose whetherto release the call, or to continue the call (block 494), in which casethe incoming call is forwarded to (block 485) and received at the mobilecommunications terminal 110 a (block 490). The user 115 a may decidewhether or not to accept the incoming call and answer.

If instead the (telephone number of the) calling user is not in the list205 b (exit branch N of decision block 492), the incoming call isblocked by the OSA application server and not forwarded to the user'smobile communications terminal 110 a (block 495), so as to preserve theremaining battery charge. The network 400, for example exploiting theIVR service 185 (or the MSC service), informs the calling user that thecalled user 115 a is momentarily unavailable (block 497), as if the user115 a was deregistered (for example, as if he/she had the mobilecommunications terminal turned off). The unavailability notification isreceived by the caller (499). As in usual cases of temporaryunavailability, the network 400 may detour the incoming call to a voicemailbox, where the calling user may leave a message, and keep memory ofthe telephone number of the caller, so as to notify (for instance via anSMS message, an MMS message or an Instant Message), at a later time, thecalled user 115 a that an incoming call was lost during the period oflow battery charge level, or a list of lost incoming calls may be sentin a similar way.

A similar behavior may be adopted in the case of an incoming SMS or MMSmessage, or the like: also in this case, the message is forwarded to theintended destination user's terminal 110 a or is blocked depending onwhether the user's terminal 110 a has notified a condition of lowbattery charge.

For the sake of simplicity, it is considered only the SMS messagedelivery case (the case of other messages being similar: for example, anMMS message usually starts with the sending of an SMS message).Referring to FIG. 1, the SMS-C 195 manages the distribution of SMSmessage: when an SMS message directed to the subscriber 115 a reachesthe SMS-C 195, the SMS-C forwards the message to the OSA applicationserver 135; the application server implements the same logic previouslydescribed for the incoming call, contacting the battery status server155 and checking whether the mobile communications terminal 110 a of theuser 115 a has notified a low battery charge condition; in case no suchsignaling has been made, or the mobile communications terminal 110 a hasnotified the reaching of the first, upper threshold TH1, the applicationserver 135 forwards the SMS message to the user's mobile communicationsterminal 110 a without performing any further control. In case themobile communications terminal 110 a has notified the reaching of thelower battery charge level threshold TH2, the OSA application server 135firstly checks if the sender user is in the second list 205 b: in theaffirmative case, the SMS message is forwarded to the user 115 a,otherwise the SMS is stored to be delivered when the battery charge ofthe terminal 110 a is restored.

Totally similar actions are performed by the SIP application server incase the user subscriber to the network service has an IMS-compliantmobile communications terminal, like the mobile communications terminal110 b. In this case, the subscriber user is assigned filtering criteria,that are for example stored in the users' profiles database (the IMSfunctionality of HSS—Home Subscriber Server), and that are exploited bythe SIP application server 150 for controlling the incomingcalls/messages directed to the subscriber user; the service logicimplemented by the SIP application server is essentially the same asthat previously described in respect of the OSA application server.

It is observed that albeit not explicitly shown in the flowchart (forthe sake of simplicity), the battery charge level monitoring clientmodule 335 manages suitable flags adapted to keep memory of the factthat the fall of the battery charge level below one or both of thethresholds TH1 and TH2 in the discharge phase (and thus, the fall of thebattery charge level below the thresholds TH1 d and TH2 d) has alreadybeen signaled to the network 400, so that the notification is sent onlyonce, the first time the battery charge level reaches or falls below therespective threshold.

Moreover, the battery charge level monitoring client module 335 isadapted to monitor the rise of the battery charge level above one orboth of the thresholds TH1 and TH2 (which, due to the hysteresis, in thecharge phase correspond to the thresholds TH2 c and TH1 c, typically asthe consequence of the battery recharge, or of a battery replacement,and to correspondingly signal such occurrences to the network 400 (viaUSSD messages, SMS messages or Instant Messages), in a way similar tothat described in the foregoing in connection with the signaling of thebattery discharge, so as to update the user's record 190 in the batterystatus server 155. Thus, after the battery is recharged or changed, andthe battery charge level returns above the threshold TH2 c or even abovethe threshold TH1 c, the mobile communications terminal 110 a notifiesthe network 400, and the “TH2” (and/or the “TH1”) flag is reset in therecord 190 at the battery status server 155; in consequence of this, thenetwork may notify the friend users (those listed in the first list 205a) that the situation of low battery charge condition has been overcomefrom the subscriber' mobile terminal and from that point on they areagain free to placing calls/sending messages, being the incomingcalls/messages directed to the user's mobile communications terminal 110a no longer blocked, at least until the battery charge level monitoringclient module 335 detects that the battery charge level is again fallenbelow the thresholds TH1 d, TH2 d.

The OSA application server can then notify the user 115 a of thetelephone numbers of calling users whose calls have been blocked.

Although the present invention has been disclosed and described by wayof some embodiments, it is apparent to those skilled in the art thatseveral modifications to the described embodiments, as well as otherembodiments of the present invention are possible without departing fromthe spirit or essential features thereof/the scope thereof as defined inthe appended claims.

For example, the number of battery charge level thresholds is not at alllimitative to the present invention. More thresholds might in fact beset, with differentiated actions taken upon reaching of each threshold.Also, just one single threshold may be adopted, e.g., the lowerthreshold TH2, and in such a case the actions of notifying the userswhose telephone numbers are in the first list 205 a blocking incomingcalls/messages from users whose telephone numbers are not in the secondlist 205 b, are undertaken upon reaching the single threshold TH2.

As another example, users of IMS-capable mobile communicationsterminals, possibly in addition to receiving the notification from thenetwork, may visualize a current battery charge level condition of otherusers in terms of, e.g., an icon, or a color of an icon displayed ontheir terminals, the icon or icon color being determined by a presenceserver that, based on the information held by the battery status server,manages flags corresponding to the battery charge level condition of theusers; by contacting the presence server, a suitable client applicationrunning at the IMS terminals of the IMS terminals users may get theinformation about the battery charge level of other users.

Furthermore, in an alternative embodiment of the invention the triggerfor the incoming call/message directed to the mobile communicationsterminal of a user that has subscribed for the network service is notset at the service subscription, being instead set dynamically by theservice logic on the application server at the HLR level, when thenetwork receives the notification of the battery charge level thresholdcrossing by the mobile communications terminal (the trigger being resetwhen the battery charge is restored); in this way, the burden on theservice logic can be reduced.

1. In a mobile communications system comprising a mobile communicationsnetwork and a battery-powered mobile communications terminal, a methodcomprising: receiving, at a mobile communications network apparatussubsystem, a notification of a low battery charge condition from thebattery-powered mobile communications terminal of a first user;retrieving, at the mobile communications network apparatus subsystem, ageographic location corresponding to an approximate geographic locationof the battery-powered mobile communications terminal at the time ofsending the notification; determining a message format of a second usercorresponding to a communications terminal of the second user; andsending a first message to the second user in the same message format ofthe second user, the first message informing the second user of thenotification of the low battery charge condition and the retrievedgeographic location.
 2. The method according to claim 1, wherein sendingthe first message to the second user comprises having the mobilecommunications network apparatus subsystem inform the second user if thesecond user places a call to thebattery-powered mobile communicationsterminal.
 3. The method according to claim 1, further comprisingmanaging an incoming communication directed to the battery-poweredmobile communications terminal based on the received notificationtherefrom.
 4. The method according to claim 3, wherein managing theincoming communication comprises: avoiding forwarding the communicationto the battery-powered mobile communications terminal if a communicationsender is not in an allowed communication sender list.
 5. The methodaccording to claim 1, further comprising: providing a notification listof users, wherein informing the second user comprises informing at leastone user on the notification list.
 6. The method according to claim 1,wherein sending the first message to the second user comprises issuingat least one of a short message service message, a multimedia messagingservice message, a voice message, an instant message, and an electronicmail message.
 7. The method according to claim 1, further comprising:setting, at the battery-powered mobile communications terminal, at leasta first battery charge level threshold and a second battery charge levelthreshold; receiving as the notification a comparison of a batterycharge level to the first and second battery charge level thresholds;and if the battery charge level is lower than the first battery chargelevel threshold, sending the first message; or if the battery chargelevel is lower than the second battery charge level threshold, sending asecond message to at least the second user.
 8. The method according toclaim 7, wherein said sending the first message or the second message isperformed automatically.
 9. The method according to claim 1, whereinsaid notification comprises at least one of an unstructuredsupplementary service data message, a short messaging service message,and a presence message.
 10. In a mobile communications system comprisinga mobile communications network and a battery-powered mobilecommunications terminal, a method comprising: receiving, at a mobilecommunications network apparatus subsystem, a notification of a lowbattery charge condition from the battery-powered mobile communicationsterminal of a first user; retrieving, at the mobile communicationsnetwork apparatus subsystem, a geographic location corresponding to anapproximate geographic location of the battery-powered mobilecommunications terminal at the time of sending the notification;informing at least one second user of the notification of the lowbattery charge condition and the retrieved geographic location;providing a list of users allowed to place calls; checking whether thesecond user is in the list; in the negative case, avoiding forwarding acall from the second user to thebattery-powered mobile communicationsterminal; and in the positive case, allowing the second user to choosewhether or not to continue with the call to the battery-powered mobilecommunications terminal, and if the second user chooses not to continuethe call, avoiding forwarding the call to the battery-powered mobilecommunications terminal.
 11. The method according to claim 10, whereinsaid list comprises at least one allowed caller specified by the firstuser of the mobile communications terminal.
 12. The method according toclaim 10, wherein said avoiding forwarding the call further comprisesforwarding the call to a mailbox associated with the first user.
 13. Themethod according to claim 10, further comprising: informing the firstuser of the calls or communications not forwarded to the battery-poweredmobile communications terminal during the low battery charge condition.14. A mobile communications system comprising a mobile communicationsnetwork apparatus subsystem adapted to: receive, from a battery-poweredmobile communications terminal of a first user, a notification of a lowbattery charge condition; retrieve a geographic location correspondingto an approximate geographic location of the battery-powered mobilecommunications terminal at the time of sending the notification;determine a message format of a second user corresponding to acommunications terminal of the second user; and send a first message tothe second user in the same message format of the second user, the firstmessage configured to inform the second user of the notification of thelow battery charge condition and the retrieved geographic location. 15.The mobile communications system according to claim 14, wherein themobile communications network apparatus subsystem is adapted to send thefirst message to the second user if the second user places a call to thebattery-powered mobile communications terminal.
 16. The mobilecommunications system according to claim 15, wherein the mobilecommunications network apparatus subsystem is further adapted to managethe call by the second user according to the received notification. 17.The mobile communications system according to claim 14, wherein themobile communications network apparatus subsystem is further adapted tomanage an incoming communication directed to the battery-powered mobilecommunications terminal based on the received notification therefrom.18. The mobile communications system according to claim 14, wherein themobile communications network apparatus subsystem is further adapted to:manage a list of users to be sent the first message informing of the lowbattery charge condition experienced by the battery-powered mobilecommunications terminal of the first user, and send to the second userthe first message if the second user is in the list.
 19. The mobilecommunications system according to claim 14, wherein the first messageto the second user comprises at least one of a short messaging servicemessage, a multimedia messaging service message, a voice message, aninstant message, and an electronic mail message.
 20. A mobilecommunications system comprising a mobile communications networkapparatus subsystem adapted to: receive, from a battery-powered mobilecommunications terminal of a first user, a notification of a low batterycharge condition; retrieve a geographic location corresponding to anapproximate geographic location of the battery-powered mobilecommunications terminal at the time of sending the notification; informat least one second user of the notification of a low battery chargecondition and the retrieved geographic location; manage a list of usersallowed to place calls to the battery-powered mobile communicationsterminal; when a call from the second user is placed, check whether thesecond user placing the call is in the list; if the second user is notin the list, avoid forwarding the call to the battery-powered mobilecommunications terminal; and if the second user is in the list, allowthe second user to choose whether or not to continue with the call tothe battery-powered mobile communications terminal, and if the seconduser chooses not to continue the call, avoid forwarding the call to thebattery-powered mobile communications terminal.
 21. The mobilecommunications system according to claim 20, wherein the list comprisesat least one allowed caller specified by the first user of the mobilecommunications terminal.
 22. The mobile communications system accordingto claim 20, wherein the mobile communications network apparatussubsystem is further adapted to forward the call not allowed to beforwarded to the battery-powered mobile communications terminal to amailbox associated with the first user.
 23. The mobile communicationssystem according to claim 20, wherein the mobile communications networkapparatus subsystem is further adapted to inform the first user of thecommunications not forwarded to the battery-powered mobilecommunications terminal during the low battery charge condition.